Motor vehicles such as pickup trucks, vans, automobiles, motor homes, etc., are typically constructed to have a pair of mutually-opposing parallel frame members or rails on which is mounted a body and front and rear bumpers. To enable towing of boats, camper trailers, motorcycle trailers, and other recreational or commercial trailers, these motor vehicles must be adapted to allow the trailer to be attached to the rear of the vehicle. Typically, a receiver ball is mounted on the center of the rear bumper of the motor vehicle, and the trailer is then coupled to the receiver ball. However, the disadvantage of this arrangement is the limited load carrying capacity of bumpers. In addition, many modern automobiles do not have rear bumpers designed to support the load of a trailer or permit attachment of a receiver ball.
As a consequence of the foregoing, trailer hitches have been developed that attach directly to the motor vehicle frame rails. This transfers the load of the trailer directly to the vehicle frame, where heavier loads can be tolerated. In addition, receiver tubes have been developed that are stronger and enable coupling with a greater variety of trailer tongues. However, there are a number of disadvantages to these types of hitches. First, these hitches are usually custom made to fit the particular vehicle, thus requiring the use of an expert craftsman in designing, constructing, and attaching the hitch to the vehicle frame. As a consequence, most vehicle owners must rely on the costly services of these skilled craftsmen. In addition, while many of these types of hitches permit adjustment in one or possibly two directions, they do not permit adjustment in all three directions, i.e., height, width, and depth. As a result, the usefulness of these hitches is limited only to the vehicles that they are sized to fit and to towing trailers that are of a suitable size and height for the hitch. Consequently, there is a need for a hitch of a universal type that can be quickly and easily fitted to a vehicle frame by the average vehicle owner and adjusted to meet the size requirements of the vehicle and the trailer to be towed, not only at the time the hitch is mounted on the vehicle, but at any time during the life of the hitch and the vehicle.